[Pdns-announce] PowerDNS Recursor 4.1.11 Released

Erik Winkels erik.winkels at open-xchange.com
Fri Feb 1 13:34:22 UTC 2019


We just released PowerDNS Recursor 4.1.11.

Since Spectre / Meltdown, system calls have become more expensive.  In addition, relevant versions of glibc turn out to implement `pthread_cond_wait` and `pthread_cond_signal` in such a way that they use multiple system calls always.
There is an optimization in glibc to improve this but it is disabled.

This new setup changes our protobuf logging so it amortizes system calls so we perform far less than one call per message.

Note that our previous `RemoteLogger` was configured in terms of how many messages it would buffer. Our new code is configured in terms of how many bytes. I have multiplied the configured numbers by 100 elsewhere (recursor config, dnsdist config) to sort of maintain parity.

In addition, the old `RemoteLogger` would buffer messages while there was no connection available. We no longer do this.

Finally new, every `reconnectTimeout` seconds we will flush our buffers opportunistically to not keep people waiting.

The changelog[1]:

- #7434: Add an option to export only responses over protobuf
- #7430: Reduce systemcall usage in protobuf logging

The tarball[2] (signature[3]) is available at https://downloads.powerdns.com/releases/  and packages for CentOS 6 and 7, Debian Jessie and Stretch, Ubuntu Bionic, Trusty and Xenial are available from https://repo.powerdns.com/  .

Please send us all feedback and issues you might have via the mailing list[4], or in case of a bug, via GitHub[5].

[1] https://doc.powerdns.com/recursor/changelog/4.1.html#change-4.1.11
[2] https://downloads.powerdns.com/releases/pdns-recursor-4.1.11.tar.bz2
[3] https://downloads.powerdns.com/releases/pdns-recursor-4.1.11.tar.bz2.sig
[4] https://mailman.powerdns.com/mailman/listinfo/pdns-users
[5] https://github.com/PowerDNS/pdns/issues/new
Erik Winkels
PowerDNS.COM BV -- https://www.powerdns.com
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